You don’t need a degree in engineering to design roller coasters, you need a degree in psychology,” said John Allen, a celebrated coaster designer. “A roller coaster is as theatrically conceived as a Broadway play.”


For years, roller coaster designers have been working hard to push our buttons. The slow climb at the start of a ride that builds anticipation, sharp twists and curves that take us by surprise, and the humps and drops that make our stomachs leap are all part of their armoury.

But now the task of maximising each rider’s enjoyment, or ‘thrill’, is turning scientific. The boffins are starting to unpick exactly what makes these rides thrilling so the roller coasters of the future will hit more of your buttons more of the time.

Scientists from the University of Nottingham recently turned the Alton Towers amusement park, in Staffordshire, into an open-air lab. They rigged up over 100 volunteers with equipment that measured everything from their heart rate to the minute muscle movements in their faces as they rode on the park’s rides. The data produced is now being sifted to uncover what riders really do, or don’t, enjoy.

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“If you have a better understanding of how people experience existing rides, it means you can make better ones,” says Professor Steve Benford, head of the School of Computer Science at Nottingham. “For instance, you may have a more subtle understanding of the relationship between a drop and the tension that builds up before it.”

Thrill unmasked

Among those collaborating with the team in Nottingham is Brendan Walker, a man described as a ‘thrill engineer’. After leaving a career designing military aircraft, he now makes a living unpicking exactly what ‘thrill’ is and how to maximise it in everything from game shows to roller coaster rides.

The early results from the research at Alton Towers have been interesting. “The heart rate is slow to react to what’s happening on the ride,” says Walker. “There’s a few seconds’ delay after the G-force and you don’t get massive spikes.” Far quicker to react to the drops and curves is skin conductivity. Often the preserve of lie detector tests, this measure reveals your anxiety level.

The only trouble is, you could design a ride to maximise the responsiveness on the skin conductivity test, but the rider might be going through sheer hell. Feelings that are completely opposite, such as excitement and fear, can produce the same physiological signs. The missing link, it turns out, is the face. Micro-movements in facial muscles, picked up through sensors, show whether someone is experiencing pleasure or sheer terror, even if they are trying to mask their true emotions.

Feel the force

So what makes a roller coaster thrilling? Well, it doesn’t take a man in a lab coat to tell you that G-forces are important. Speeding up, slowing down and turning tight corners all produce potentially thrilling sensations. But getting the balance between a thrilling ride and dangerous G-forces is crucial.

It’s here that ride designers need to know their physics. Exactly what the human body can cope with depends on the direction of the force and its duration. Studies carried out in NASA centrifuges have revealed an upper limit of 17G under acceleration (known as eyeballs in) and 12G under deceleration (eyeballs out), for several minutes without anyone passing out. Ride designers set their limits much lower so as not to scare the wits out of their customers. “We would never have more than 6G [acceleration],” says Andreas Wild, an engineer with Stengel Engineering in Germany, a company that’s helped design over 500 rides. “I think most are between 4.5 and 5G.”

As well as the overall G-force, the rate of change in G-force – known as the ‘jerk’ – also adds that thrill factor. Walker’s tests reveal that skin conductivity responds rapidly to this. Walker hasn’t confined his research to monitoring biodata on roller coasters. Some of his work has been inspired by a study by Jack Katz, Professor of Sociology at the University of California in Los Angeles. Katz picked through interviews with petty criminals to get an understanding of exactly what got their adrenaline pumping.

For his own version of the research, Walker set up to gather stories of thrilling experiences. He was sent anecdotes about everything from someone who cracked an egg on their mum’s head, to a cross-dresser going to his first transvestite bar. Walker discovered that while some activities simply created a huge increase in excitement, the thrill could be magnified if a little fear was thrown into the mix. On a roller coaster, this cocktail of fear and excitement is vital.

Thankfully, that fear is down to perceived danger, rather than genuine risk – it’s estimated that the chance of getting a serious injury at a theme park is one in 1.5 billion. But the illusion of danger is vital. “It’s crucial to create a contrast between pleasure and displeasure,” says Walker. “But there’s a fine line. You have to give people a sniff of fear before the thrilling experience, and I think crafting those moments is going to become increasingly important.”

Robotic rollers

One company planning to put Walker’s research into practice is Robocoaster. Nine years ago its founder, Gino De-Gol, had the idea of taking the robotic arms used in manufacturing and turning them into a ride. Today his rides are enjoyed by thousands of people across Europe and the US. De-Gol, MD of Robocoaster, is using the findings in Walker’s research to help design new manoeuvre sequences and new rides.

According to De-Gol, in the future, ride passengers will be able to have their heart rates and skin conductivity monitored when they’re on a ride, so it can be adjusted in real-time to maximise the thrill. The rides he’s currently developing, with his robotic arms attached to traditional roller-coaster carriages, would be well suited to this approach. The arm carrying a rider showing high anxiety levels could move more steadily than one carrying an adrenaline junkie, for instance.
As we pin down that thrill factor in unprecedented detail, theme parks could well be on the verge of a revolution. But will ride designers still strive to break new records? “The premise of higher, faster, more extreme rides will become less of a selling point,” says Walker. “It will be more about how the rides are put together – the choreography.” So in the theme park of the future, the psychologist really will be king.


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Andy is a Senior Lecturer in Science Communication at the University of the West of England in Bristol, Programme Leader of the MSc in Science Communication and an award-winning journalist